Low Blood Pressure
Blood pressure is the force of blood pushing against the walls of youras the heart pumps blood. It is usually described as two numbers: and . The numbers record blood pressure in millimeters of mercury (mm Hg), with systolic listed above diastolic. For most adults, a healthy blood pressure is usually less than 120/80 mm Hg. Low blood pressure is blood pressure that is lower than 90/60 mm Hg.
Some people have low blood pressure all the time, and it is normal for them. Other people experience a sudden drop in blood pressure or have low blood pressure that may be linked to a health problem. Many systems of the body, including organs, hormones, and nerves, regulate blood pressure. For example, thesends the “fight-or-flight” signal that, depending on the situation, tells the heart and other systems in the body to increase or decrease blood pressure. Problems with the autonomic nervous system, such as in Parkinson’s disease, can cause low blood pressure.
Other causes of low blood pressure include medicines, bleeding, aging, and conditions such as dehydration, pregnancy, diabetes, and heart problems. Older adults have a higher risk for symptoms of low blood pressure, such as falling, fainting, or dizziness upon standing up or after a meal. Older adults are also more likely to develop low blood pressure as a side effect of medicines taken to control high blood pressure.
For many people, low blood pressure goes unnoticed. Others feel light-headed, confused, tired, or weak. You may have blurry vision, a headache, neck or back pain, nausea, or heart palpitations. Sitting down may relieve these symptoms. If blood pressure drops too low, the body’s vital organs do not get enough oxygen and nutrients. When this happens, low blood pressure can lead to , which requires immediate medical attention. Signs of shock include cold and sweaty skin, rapid breathing, a blue skin tone, or a weak and rapid pulse. If you notice signs of shock in yourself or someone else, call 9-1-1.
Your doctor will use a blood pressure test to diagnose low blood pressure. Other tests may include blood, urine, or imaging tests and a tilt table test if you faint often. You may not need treatment for low blood pressure. Depending on your signs and symptoms, treatment may include drinking more fluids, taking medicines to raise your blood pressure, or adjusting medicines that cause low blood pressure. Recommended lifestyle changes include changing what and how you eat and how you sit and stand up. Your doctor may also recommend compression stockings if you have to stand for long periods.
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Research for Your Health
Improving health with current research
- Low Blood Pressure
Learn about the following ways the NHLBI continues to translate current research into improved health for people with abnormally low blood pressure. Research on this topic is part of the NHLBI’s broader commitment to advancing heart and vascular disease scientific discovery.
- Testing Treatments for Cardiac Arrest and Trauma. The Resuscitation Outcomes Consortium (ROC) clinical trial network tested treatments to address high morbidity and mortality rates from out-of-hospital cardiac arrest and severe traumatic injury. ROC investigators compared different strategies for supplemental fluids in trauma patients who have low blood pressure. Other ROC studies found a link between low blood pressure readings and the need for emergency procedures.
- Understanding How Low Blood Pressure Affects Diverse Populations. NHLBI-supported researchers are studying low blood pressure in different populations. Investigators in the NHLBI’s Atherosclerosis Risk in Communities Study (ARIC) found that people who have low blood pressure when standing up, known as orthostatic hypotension, are at higher risk for stroke. In a follow-up study of NHLBI’s Honolulu Heart Program, researchers found older Japanese men who had orthostatic hypotension were nearly twice as likely to die within the next four years as those who did not have orthostatic hypotension. NHLBI’s Cardiovascular Health Study (CHS) found that orthostatic hypotension was common in older adults, increases with age, and is linked to cardiovascular diseases.
Learn about some of the pioneering research contributions we have made over the years that have improved clinical care.
- Certain combinations of medicine can cause dangerous drops in blood pressure. NHLBI-supported research found that combining a muscle relaxant with other commonly prescribed medicines, including an antibiotic and a medicine for depression, can cause dangerously low blood pressure.
- Investigating ideal systolic blood pressure for people who have heart failure. NHLBI-funded research found that hospitalized older patients who have heart failure with preserved ejection fraction may not do well with systolic blood pressure readings that are considered healthy in other people. More research is needed to determine optimal systolic blood pressure targets for these patients. Visit Low Blood Pressure Associated with Poor Outcomes in Patients with Heart Failure with Preserved Ejection Fraction for more information.
- Low blood pressure in children after cardiac arrest is a sign of worse outcomes. Researchers supported by the NHLBI evaluated data on children who were resuscitated after a cardiac arrest. The researchers found that children who had low blood pressure—determined to be below the fifth percentile of systolic blood pressure readings for children of the same sex and age—in the first six hours after cardiac arrest, had a higher risk of serious and life-threatening complications.
Advancing research for improved health
- Low Blood Pressure
In support of our mission, we are committed to advancing research on low blood pressure in part through the following ways.
- We fund research. The research we fund today will help improve our future health. Our Division of Cardiovascular Sciences and its Vascular Biology and Hypertension Branch oversee much of the research we fund on the regulation of blood pressure, helping us to understand and treat low blood pressure. The Center for Translation Research and Implementation Science supports research to translate these discoveries into clinical practice. Search the NIH RePORTer to learn about research the NHLBI is funding on low blood pressure.
- We stimulate high-impact research. The NHLBI Strategic Vision highlights ways we may support research over the next decade.
Learn about exciting research areas the NHLBI is exploring about low blood pressure.
- Exploring a new method of blood pressure control for use in surgery. Surgeons often use medicines to control blood pressure during surgery, but the effects can vary from patient to patient and lead to complications. NHLBI-supported researchers are looking into nerve stimulation as an alternative method for controlling blood pressure during surgery.
- Investigating ways to prevent low blood pressure and falls in older adults. Dips in blood pressure that happen when standing up can be due to too much high blood pressure medicine. The NHLBI supports research into this complication and the risk of falls, as well as the testing of new strategies to prevent blood pressure from dropping too low.
Participate in NHLBI Clinical Trials
We lead or sponsor research on low blood pressure. See whether you or someone you know is eligible to participate in our.
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After reading our Low Blood Pressure Health Topic, you may be interested in additional information found in the following resources.
Related Health Topics
- Low Blood Pressure
- Low Blood Pressure
- Diabetes (National Institute of Diabetes and Digestive and Kidney Diseases)
- Dysautonomia (Autonomic Dysfunction) (National Institute of Neurological Disorders and Stroke [NINDS])
- Orthostatic Hypotension Information Page (NINDS)
- Low Blood Pressure (National Library of Medicine [NLM], MedlinePlus)
- Shock (NLM, MedlinePlus)
- Shock resource guide (NLM, MedlinePlus)